deletions | additions       diff --git a/using_rotation_curves.tex b/using_rotation_curves.tex  index 566601a..577d294 100644  --- a/using_rotation_curves.tex  +++ b/using_rotation_curves.tex 
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\subsection{Using Rotation Curves and Velocity Measurements to Place Nessie in 3D} Ever since velocity-resolved observations of stars and gas have been possible, astronomers have been modeling the rotation pattern of the Milky Way. Using a measured rotation curve for the Milky Way's gas, e.g., \citep{McClureGriffiths2007}, one can translate observed LSR velocities to a unique distance in the Outer Galaxy, and to one of two possible (``Near" or ``Far") distances toward the Inner Galaxy. Figure \ref{fig:topview} shows iso-$v_{LSR}$ contours toward the Inner Galaxy, around the longitude range of Nessie, superimposed on the data-driven cartoon of our current understanding of the Milky Way's structure (xxBenjamin will suggest how to reference this work by Hurt, Benjamin, Dame, et al.xx). It is clear from Figure \ref{topview} \ref{fig:topview}  why a Near-Far distance ambiguity exists, and also that velocities associated with the near-side of the Scutum-Centaurus Arm at Nessie's longitude range should be near 40 \kms. Combining the modern measurements of the Sun's height above the plane ($z\sim 25$ pc), with the IAU galactic coordinate definitions as described in \S \ref{topview}, we can determine where the mid-Plane of the Galaxy should appear in the $(l^{II}, b^{II})$ system at any particular distance from the Sun. Figure \ref{fig:coloredlines} shows where the Scutum-Centaurus Arm would appear on the Sky (for a distance to SrgA* of 8.4 kpc, a rotation speed for the Milky Way of 239 \kms, and (U,V,W) motion for the Sun of 11.1, 12.4, and 7.2 \kms, respectively). As its caption explains in detail, Figure \ref{fig:coloredlines}'s colored lines are associated with the near part of the Scutum-Centaurus Arm (shown as short, yellow-greeen line segment in Figure \ref{fig:topview}). For reference, white lines in Figure \ref{fig:coloredlines} show the Sky position of the far part of the Scutum-Centaurus arm in the same longitude range (shown as a white chalk line in Figure \ref{fig:topview}). The dashed colored line in Figure \ref{fig:coloredlines}, indicating the predicted position of the Galactic Plane on the Sky at the distance to the near side of the Scutum-Centaurus Arm, passes almost directly through Nessie. Solid colored lines show 20 pc above and below the Plane at the distance to the Scutum-Centaurus Arm, so Figure \ref{fig:coloredlines} makes it is very clear that Nessie lies within just a few pc of the Plane, along its entire length. This is either an extremely fortuitous coincidence, or an indication that Nessie is tracing a significant feature that lies ``exactly" within the Galactic Plane.